'Yao bu yao zuoxia (Do you want to sit down) ?' Cindy Hung-kun asked a five-year-old expat child at the Woodland Montessori Pre-School in Mid-Levels. The others around seemed oblivious to the 'foreign' language being used.

After all, this is a bilingual class, the school's first. Like other classes, children of varying ages engage in tasks alone or together under teachers' observation. The difference is that two languages are spoken, one by a native English-speaker and the other by Ms Hung, a native of Shenyang in northeastern China.

Turning to another expat child, Ms Hung said: 'Fang hui qu ( put it back),' instructing him to put a wooden pole back in its original position. She has few worries that her simple instructions will not be understood. 'If they study with us for a year, they will be able to understand daily instructions in Putonghua and say simple words about animals, fruits and colours, or say 'My name is ...', 'I love mummy',' she said.

On top of the daily contacts with Ms Hung, all children also have a half-hour Putonghua lesson each week.

The Montessori class is but one example of the rising number of classrooms where extensive time is devoted to learning Putonghua, set to become the predominant element of bilingual education in Hong Kong, alongside English and replacing Cantonese.

At Rightmind Kindergarten in Pokfulam, the three-hour class time is equally split between Putonghua and English. The children learn Chinese through flash cards, beginning with characters, couplets, then phrases, and later short sentences.

The characters are organised into 50 subjects covering diverse areas from natural sciences to history. Throughout the four-year curriculum, from pre-nursery to K3, they are also exposed to 4,000 English words.

Programme director Thomas Ho Kwong-hung expressed confidence in the students' bilingual abilities, saying: 'Our students are used to speaking the right language to the right teacher.'

Early immersion was very effective for developing proficiency in two languages, said Shirley Lee, principal of the Independent Schools Foundation (ISF) Academy, set up in 2003.

At ISF, Putonghua is used for most subjects, including ICT, guided discovery and project work from years one to three, accounting for 70 per cent of instruction time. The amount of teaching in English increases as children progress to senior grades, reaching 70 per cent at Grade Seven.

'We recognise the fact that children have the strongest ability in memorisation before age seven while their reasoning ability is being developed and design our Chinese instruction accordingly,' said Ms Lee, a trained Chinese foreign language teacher.

From Grade One, children are immersed in learning Chinese classical texts and poetry, exposing them to the richness of Chinese culture and thought.

ISF's adoption of the International Baccalaureate curriculum framework further allowed children to use the various language skills - reading, writing, listening and speaking - in a meaningful context, she said.

Kindergartens that don't take the bilingual approach, meanwhile, normally offer some exposure to Chinese to help children gain an early ear for it. Pupils at Highgate House School, for example, have daily five to 10 minutes of Putonghua 'circle time' involving the singing of rhymes that helps them pick up the tones.

Jose Lai Chan Sau-hing, senior instructor at Chinese University of Hong Kong's English Language Teaching Unit, said learning languages at an early age in a positive environment was ideal. 'Children can sort out the differences between two languages over time, provided there is enough input from both, and not mixed-code teaching. They will not be confused as long as there is a strong linguistic environment in the school,' she said.